Described below is an arrangement for the air conditioning of subassemblies, in particular electrical subassemblies, in a closed housing.
Air conditioning solutions are known in which fans are used for the ventilation or air conditioning of electrical subassemblies in base stations.
FIG. 3 shows an exemplary first air conditioning solution according to the related art, with reference to a mobile telephony base station.
In the case of this air conditioning solution a radial fan RL is used as a fan.
Electrical subassemblies BG which must be cooled or heated depending on the ambient temperature T are arranged on a rack BGT in the interior of a base station housing BS.
By operation of the radial fan RL, air ZL in the form of incoming air is sucked into the interior of the base station housing BS via a filter system FS.
In this arrangement the filter system FS prevents any unwanted penetration of dust and contaminant particles. This is necessary because air humidity combined with the contaminant particles within the base station housing BS would result in corrosion.
The air ZL reaches the subassemblies BG via a switchable heating entity HZ, and can therefore be used for both cooling and heating the subassemblies BG. The air ZL which is used for the air conditioning of the subassemblies BG is then guided into the interior of the radial fan RL via an inlet RLE of the radial fan RL.
The base station housing BS has a so-called “standard” backplane RW which is divided into chambers KA. This backplane RW is embodied in such a way that the air ZL which is used for the air conditioning reaches a chamber KA of the backplane RW from the interior of the base station housing BS via an outlet RLA of the radial fan RL.
The chamber KA is in turn connected to the environment UM, such that the air ZL which is used for the air conditioning of the base station housing BS is guided into the environment UM as discharge air.
In the case of ambient temperatures T of typically T<0° Celsius, the air ZL is heated by the heating entity HZ in order that selected subassemblies BG can be heated accordingly. To that end, electrical heating entities HZ which are assigned in each case in proximity to the subassemblies BG and can be controlled independently of each other are provided in the interior of the base station housing BS.
In the case of this air conditioning solution, additional costs are incurred during operation as a result of the electrical heating energy that is required.
FIG. 4 shows an exemplary second air conditioning solution according to the related art, with reference to a mobile telephony base station. In this case, too, a radial fan RL is again used as a fan.
In comparison with the embodiment described in FIG. 3, a modified backplane RWM is used here, the backplane being likewise divided into chambers KA.
Each chamber KA has a further opening or connection VE which can be closed in a controllable manner by a flap KL. The flap KL connects the chamber KA to the interior of the base station housing BS.
The flap KL allows air, which has already been heated by the subassemblies BG in a first pass, to be routed out of the chamber KA back into the interior of the base station housing BS, and to be used for heating the subassemblies BG again in a second pass.
In other words, air ZL which is used for the air conditioning undergoes a cyclical flow:                air ZL which is sucked in arrives at the radial fan RL via the subassemblies BG and the heating entities HZ that are assigned in each case;        the air arrives in respective chambers KA of the backplane RWM via the outlet RLA of the radial fan RL;        air from the chambers KA can then—controlled by the flap KL—be used again for the air conditioning of the subassemblies BG and/or diverted into the environment UM.        
The requirement for electrical heating energy is reduced by the flaps KL and the chambers KA and the air circulation that can be controlled thereby. In addition, a reduction of the relative air humidity can be achieved in the interior of the base station housing BS.
The controllable flaps KL are driven by electric motors M, these being controlled by what is called a “controller board”. The “controller board” controls the air conditioning in the interior of the base station housing BS or the air conditioning of the subassemblies BG with the aid of sensors which are not shown here.
However, this second air conditioning solution generally does not allow retrofitting to existing base station housings which are already in service. It is not usually possible to replace the backplane of the base station housing with a modified backplane of the type described hereintofore.